The terminal potential difference of a cell is greater than its emf when:
1. | A battery of less emf is connected in its series. |
2. | A battery of higher emf is connected in its series. |
3. | A battery of higher emf is connected in its parallel. |
4. | A battery of less emf is connected in its parallel. |
A battery is charged at a potential of \(15\) V for \(8\) hours when the current flowing is \(10\) A. The battery on discharge supplies a current of \(5\) A for \(15\) hours. The mean terminal voltage during discharges is \(14\) V. The "Watt hour" efficiency of the battery is:
1. \(80\%\)
2. \(90\%\)
3. \(87.5\%\)
4. \(82.5\%\)
Five equal resistances each of resistance \(R\) are connected as shown in the figure below. A battery of \(V\) volts is connected between \(A\) and \(B\). The current flowing in \(AFCEB\) will be:
1. \(\frac{V}{R}\)
2. \(\frac{V}{2R}\)
3. \(\frac{2V}{R}\)
4. \(\frac{3V}{R}\)
The specific resistance of a conductor increases with:
1. | increase in temperature. |
2. | increase in cross-section area. |
3. | increase in cross-section and decrease in length. |
4. | decrease in cross-section area. |
For a cell, the terminal potential difference is \(2.2\) V when the circuit is open and reduces to \(1.8\) V when the cell is connected to the resistance of \(R = 5~\Omega\). The internal resistance of cell (\(r\)) is:
1. | \(\dfrac{10}{9}~ \Omega\) | 2. | \(\dfrac{9}{10}~ \Omega\) |
3. | \(\dfrac{11}{9}~ \Omega\) | 4. | \(\dfrac{5}{9}~ \Omega\) |
In a Wheatstone bridge, all four arms have equal resistance \(R.\) If the resistance of the galvanometer arm is also \(R,\) the equivalent resistance of the combination is:
1. | \(R/4\) | 2. | \(R/2\) |
3. | \(R\) | 4. | \(2R\) |
The current in \(8~\Omega\) resistance is (in the figure below):
1. \(0.69\) A
2. \(0.92\) A
3. \(1.30\) A
4. \(1.6\) A
When three identical bulbs are connected in series, the consumed power is \(10\) W. If they are now connected in parallel then the consumed power will be:
1. \(30\) W
2. \(90\) W
3. \(\frac{10}{3}\) W
4. \(270\) W
If there are two bulbs of (\(40~\text{W},200~\text{V}\)), and (\(100~\text{W},200~\text{V}\)), then the correct relation for their resistance is:
1. \(R_{40}<R_{100}\)
2. \(R_{40}>R_{100}\)
3. \(R_{40}=R_{100}\)
4. no relation can be predicted
A car battery of emf \(12~\text{V}\) and internal resistance \(5\times 10^{-2}~\Omega\) receives a current of \(60~\text{A}\) from an external source. The terminal voltage of the battery is:
1. | \(12~\text{V}\) | 2. | \(9~\text{V}\) |
3. | \(15~\text{V}\) | 4. | \(20~\text{V}\) |